Artificial breathing atmosphere and treatment of persons exposed to abnormal pressures



Patented Oct. 4, 1927.

UNITED STATES PATENT OFFICE.

WILLIAM P. YANT, OF PITTSBURGH, PENNSYLVANIA; BOYD R. SAYEBS, OF WASH- INGTON, DISTRICT OF COLUMBIA; AND JOEL H. HILIDEBRAND, OF ALAMEDA, CALI- FOBNIA.

ARTIFICIAL BREATHING ATMOSPHERE AND TREATMENT OF PERSONS EXPOSED TO ABNORMAL PBESSURES.

Re Drawing.

This invention relates to artificial atmospheres and the use of the same in treating ersons exposed to abnormal pressures and is particularly useful in connection with div- 6 ing or caisson work.

Notwithstanding the increasing demand for a greater range in deep sea diving and other submarine operations, very limited progress has been made toward materially 1 extending the time limits at which men are enabled to work under the extremely advei se pressure conditions encountered in such operations. It has been attempted to construct diving suits of a nonielding character so that the man encased t erein might work at atmospheric pressure, but these devices, because of mechanical difficulties, clumsiness and lack of freedom of the diver for performing work, have been found generally unsatisfactory. The usual apparatus in which the diver is subjected to an air pressure equal to that of the water at the depth of operation has been found the only practical suit for submarine operations. At the present time the practical working limit is at a depth of about two hundred feet of water. At such pressure the diver is subjected to a pressure of aproximately 100 pounds per square inch, or a total body pressure of about 230,000 pounds. This pressure in itself is not harmful since the body builds up an internal balancing pressure principally throu h the respiratory and circulatory system of the body.' The body fluids and tissues act like a liquid which is exposed to gaseous pressure and absorb the gas until a pressure balance is attained. It should be mentioned that a greater time la occurs, but in this respect onl does the ody act in any materially di erent fashion from a liquid under ressure. This building up of ressure wlthin the body can be accomplis ed with great rapidity and there is little or no physiological danger attendant upon the lowering of the diver to his field of operations, since the body is in a condition of undersaturation.

It has been known for many years, however, that serious difficulties are encountered u on the decompressing operation or the step of raising the diver back to the surface. If the decompression is brought about over too short a time period the diver is subjected to Serial No. 31,690.

cramps and the severe acute symptoms known as the bends or caisson workers disease. If the tlme is greatly reduced paralysis or death may result; Experiments show that these effects are due to the release of gas bubbles within the body when the reduction of pressure outside the body has been brought about and the body acts like a solution in attempting to dispose of the excess internal pressure. If these gas bubbles occur in the blood vessels they may collect in the heart and the circulation may thus be impaired or stopped. If the occur in the brain or the spinal cord paralysis results.

It has therefore been necessary to use extreme care in decompressing persons who have been exposed to high pressure so that the excess pressure may pass off without the formation of harmful gas bubbles in the body. By the law of partial pressures any as which goes into solution in the body liqulds or tissues'will build up an internal pressure to correspond to the external pressure which would be exerted by that same gas alone if it were occupying the space in which the body is confined. Accordingly the internal body pressure during decompression is made up of a component of pressure correspondin to the excess oxygen content of the body an a component corresponding to the excess nitrogen content of the body. The excess oxygen, within a limited pressure range, can be used up by the cells in the body metabolism. The nitrogen, however, must pass ofl principally, if not entirely, through the lungs and the decompression rate must be so regulated as to prevent the dangerous bubbling effect above described. The permissible decompression rate increases with the depth since the quantity of gas absorbed by the body increases directly with the pressure. For example, the body fluids and tissues when at equilibrium with ten atmospheres pressure will have in solution ten times the volume of gas they would contain at one atmosphere, assumin the fluids and tissues to act as perfect liquids. There is a certain variation from this, but'experiments have shown that such conditions are at least approximated in the body. This means that in decompressing from say ten atmospheres, nine times the normal nitrogen content mult be removed. The time required for such decompression from pressures greater than 200 feet of water is found in practice to be so great as compared with the useful work period that diving to greater depths is impractical except in rare emergencies.

We provide an artificial atmosphere, including oxygen and a gas having a greater rate of difl'usibility than nitrogen or less soluble in the body than nitrogen, or both. Helium is the preferred gas employed. The diffusion rate of helium is about twice that of nitrogen and its solubility in the body is about one half that of nitrogen. The greater diifusibility of helium is due to its lower molecular weight, the rates of diffusion of gases from liquids varying inversely as the square roots of their molecular weights. Because of its greater diffusibility, the helium, during decompression, passes out of the body about twice as fast as nitrogen. Because of its lesser solubility, only about half as much helium goes into solution in the body tissues as would nitrogen. Therefore, any bubbling which might occur on decompression would be approximately one-fourth as great as that due to nitrogen.

Actual experiments have shown that with an artificial atmosphere of oxygen and helium, the decompression time may be reduced to one fourth or one fifth of that now necessary where ordinary air is used. Becauseof such reduced decompression time, the field or commercial diving may be extended to depths considerably below those now considered practicabie.

The artificial atmosphere may be used throughout the period during which the diver is exposed to the high pressure. It will be seen, however, that in caisson work, the cost of using helium would be very high. The advantages of our invention, however, may be secured by substituting the artificial atmosphere during the decompression period only. As above pointed out, the compression operation not injurious, since the body is in an undersaturated condition and is merely absorbing the gases. A caisson worker or diver may therefore be compressed in the ordinary manner and work in an atmosphere of oxygen and nitrogen without harm. Then when it is desired to decompress, a mixture consisting of oxygen and helium may be supplied. \Vhen this atmosphere is substituted for air, then by the law of partial pressures, the effect on the nitrogen dissolved in the body is that of a nitrogen vacuum, and the nitrogen will rapidly diffuse out of the body. The total pressure, of course, is made up by the partial ressure of the helium which is substitute for the nitrogen, so that bubbling will not occur. During this process, the nitrogen in the bodv will be replaced to some extent by the helium which, however, is more rapidly difiusible from the body as the decompression proceeds.

Also, the advanta es of our invention may be secured by emp oying the artificial atmosphere of oxygen and helium, even after the man has been decompressed. It is a well known fact that the bends may not occur until some five or six hours after decompression has occurred. When this occurs the subject may be reeompressed and then decompressed in an atmosphere of helium and oxygen. This will increase the tendency of the nitrogen to pass out of the body and to prevent t e recurrence of harmful bubbling.

While helium is the best gas known to us at the present time for this urpose, other inert, respirable gases which ave a. greater rate of diifusibility than nitrogen or a lesser solubility in the bodg than nitrogen, or both, may be employed. or example, hydrogen, which has a very low molecular weight, may be employed, although considerable danger would be attendant upop its use because of its great inflammability. Neon is another gas whose molecular weight is less than that ,of nitrogen and which might be employed if suflicient quantity were available.

While it is preferred to use an artificial atmosphere consisting principally, if not entirely, of oxygen and helium (or the other inert gas employed), the artificial atmosphere may be made up by diluting ordinary air with helium or the other inert as, which, as we shall hereinafter point out, as the further ell'eet of preventing oxygen poisoning. Or the artificial atmosphere may consist of oxygen and nitrogen together with helium or the other inert gas. hen such mixtures are used, the partial pressure of the nitrogen will be reduced by the admixture of'helium, and the advantages of an oxygen-helium atmosphere will be obtained, although of a somewhat impaired degree.

We have also discovered that the so-called oxygen poisoning may be prevented by supplying the diver or caisson worker with an atmosphere containing a reduced proportion of oxygen as compared with the atmospheric air.

Under the smaller pressures encountered in compressed air work, oxygen poisoning is not articularly serious or noticeable, since the b0 y can accommodate itself to a limited increase in concentration of absorbed oxygen. On the other hand, if the pressure is increased say to ten atmospheres, the partial pressure of the oxygen is increased ten times, and the concentration of oxygen in the body may cause oxygen poisoning, particularly if the driver is exposed to it for a considerable period of time. Oxygen poisoning may be prevented by diluting the atmosphere supplied with an inert gas to lower the proportion of oxygen below that of atmospheric air. The inert gas so supplied, and particularly in the case of a diver where a relatively small quantity is required, is preferably helium, since the helium will not only serve as a diluent, but'will serve as an aid to permit more rapid decompression. On the other hand, where large quantities of air are required, as in caisson work, a cheaper diluent may be employed, such, for example, as nitrogen, in order to prevent oxygen poisoning. Where nitrogen is used as a diluent, it is preferred to employ some gas such as helium as an aid in decompression.

The human body can accommodate itself to an oxygen content of from about 15 to 100% at a pressure of one atmosphere. The partial pressure of the oxygen increases directly with the pressure applied to the atmosphere breathed, so that under compression the body may be subjected to an oxygen concentration greater than that of pure oxygen at atmospheric pressure. For example, if atmospheric air be compressed ten times, the body will be subjected to absolute oxygen pressure of about 2.1 atmospheres. Therefore, in making the respirable mixtures for diving or other compressed air work, the oxygen content should be calculated so that the oxygen concentration is within the limits above set forth. For example, if a pressure of ten atmospheres is to be employed, the oxygen content should be between 1.5 and 10% of the volume of the compressed gas. Preferably the oxygen content is between .5 and 1 atmosphere absolute pressure. In practical use of atmospheres containing low percentages of oxygen by volume for high pressure diving or other compressed air work, it is necessary to increase the volume percent of oxygen at the lower transition pressures during compression and decompression.

While we have described the preferred ways of carrying out our invention, and particularly as embodied in the use of helium, it is to be understood that the invention is not thus limited but may be otherwise embodied within the scope of the following claims.

\Ve claim:

1. A respiratory atmosphere containing a percentage of oxygen less than that in air, and such that when breathed under supernormal pressures irritation to the respiratory tract or oxygen poisoning will not occur.

.2. A respiratory atmosphere composed principally of oxygen and helium, the percentage of oxygen being less than that in air, and such that when breathed under supernormal pressures irritation to the respiratorytract or oxygen poisoning will not occur.

3. A respiratory atmosphere composed having a greater rate of ditl'usibility than nitrogen, the percentage of oxygen being less than that in air, and such that when breathed under supernormal pressures irritation to the respiratory tract or oxygen poisoning will not occur.

5. A respiratory atmosphere composed principally of oxygen and helium, the percentage of oxygen being less than that in air, and such that the partial pressure of oxygen in the composition will not exceed 1 atmosphere absolute pressure when breathed at pressures greater than 75 pounds per square inch absolute.

6. In the treatment of persons exposed to supernormal pressures, the step consisting in supplying to such persons an artificial respiratory atmosphere containing a percentage of oxygen less than that in air, and such that when breathed under supernormal pressures irritation to the respiratory tract or oxygen poisoning will not occur.

7. In the treatment of persons exposed to supernormal pressures, the step consisting in supplying to such persons an artificial respiratory atmosphere composed principally of oxygen helium, the percentage of oxygen being less than that in air, and such that when breathed under supernormal pressures irritation to the respiratory tract or oxygen poisoning will not occur.

8. In the treatment of persons exposed to supernormal pressures, the step consisting in supplying to such persons an artificial respiratory atmosphere composed principally of oxygen and a gaseous diluent having a lower solubility in body tissues and liquids than nitrogen, the percentage of' oxygen being less than that in air, and such that when breathed under supernormal pressures irritation to the respiratory tract or oxygen poisoning will not occur.

9. In the treatment of persons exposed to supernormal pressures, t e step consisting in supplying to such persons an artificial respiratory atmosphere composed principally of oxygen and a gaseous diluent having a greater rate of diliusibility than nitro en, the percentage of oxygen being less t an that in air, and such that when breathed under supernormal pressures irritation to the respiratory tract or oxygen poisoning will not occur.

10. In the treatment of persons exposed to supernormal pressures, the step consistin in supplying to such persons an artificia respiratory atmosphere composed principally of oxygen and helium, the percentage of oxygen being such that the partial pressure of oxygen in the composition will not ex ceed 1 atmosphere absolute pressure when breathed at pressures greater than 75 pounds per square inch absolute.

11. In the treatment of persons undergoing extreme changes in pressure, the steps which consist in supplying to such persons, while under compression, a respiratory atmosphere composed principally of oxygen and nitrogen, and supplying, while under decompression, a respiratory atmosphere composed principally of oxygen and helium.

12. In the treatment of persons undergoing extreme changes in pressure, the steps which consist in supplying to such persons,

while under compression, a respiratory atmosphere composed principally of oxygen and nitrogen, and supplying, while under decompression, a respiratory atmosphere composed principally of oxy en and a aseous diluent havin a lower solubility in body tissues and liqui s than nitrogen.

13. In the treatment of persons undergoing extreme changes in pressure, the steps which consist in supplying to such persons, while under compression, a respiratory atmosphere composed principally of oxygen and nitrogen, and supplying, while under decompression, a respiratory atmosphere composed principally of oxygen and a gaseous diluent having a greater rate of diffusibility than nitrogen.

14. In the treatment of persons undergoing extreme changes in pressure, the steps which consist in supplying to'such persons while under compression, a respiratory atmosphere composed principally of oxywen and nitrogen, the percentage of oxygen eing less than that in air and such that when breathed under supernormal pressures irritation to the respiratory tract or oxygen oisoning will not occur, and supplying, while under decompression, a respiratory atmosphere composed principally of oxygen and helium.

15. In the treatment of persons undergoing extreme changes in pressure, the steps which consist in supplying to such persons while under compression a respiratory atmosphere composed principally of oxygen and nitrogen, the percentage of oxygen being less than that in air and such that when breathed under supernormal pressures irritation to the respiratory tract of oxygen poisoning will not occur, and supplying, while under decompression, a respiratory atmospherecomposed principally of oxygen and helium, the percentage of oxygen being less than that-in air and such that when breathed under supernormal pressures, irriration to the respiratory tract or oxygen poisoning will not occur.

16. In the treatment of persons undergo ing extreme changes in pressure, the steps which consist in supplying to such persons while under compression a respiratory atmosphere composed principally of oxygen and nitrogen, the percentage of oxygen being less than that in air and such that when breathed under supernormal pressures irritation to the respiratory tract or oxygen poisoning will not occur, and supplying, while under decompression, a respiratory atmosphere composed principally of oxygen and a gaseous diluent having a solubility in body tissues and liquids less than that of nitrogen.

17. In the treatment of persons undergoing extreme changes in pressure, the steps which consist in supplying to such persons while under compression a. respiratory atmosphere composed principally of oxygen and nitrogen, the percentage of oxygen being less than that in air and such that when breathed under supernormal pressures irritation to the respiratory tract or oxygen poisoning will not occur, and supplying, while under decompression, a respiratory atmosphere composed principally of oxygen and a gaseous diluent having a greater rate of dillusibility than nitrogen.

In-testimony whereof we have hereunto set our hands.

WILLIAM P. YANT. BOYD n. SAYERS. JOEL H. HILDEBRAND.

Gil

ing extreme changes in pressure, the steps which consist in supplying to such persons,

While under compression, a respiratory atmosphere composed principally of oxygen and nitrogen, and supplying, while under decompression, a respiratory atmosphere composed principally of oxy en and a aseous diluent havin a lower solubility in ody tissues and liquids than nitrogen.

13. In the treatment of persons undergoing extreme changes in pressure, the steps which consist in supplying to such persons, while under compression, a respiratory atmosphere composed principally of oxygen and nitrogen, and supplying, while under decompression, a respiratory atmosphere composed principally of oxygen and a gaseous diluent having a greater rate of diffusibility than nitrogen.

14. In the treatment of persons undergoing extreme changes in pressure, the steps which consist in supplying to such persons while under compression, a respiratory atmosphere composed principally of oxygen and nitrogen, the percentage of oxygen being less than that in air and such that when breathed under supernormal pressures irritation to the respiratory tract or oxygen poisoning will not occur, and supplying, while under decompression, a respiratory atmosphere composed principally of oxygen and helium.

15. In the treatment of persons undergoing extreme changes in pressure, the steps Certificate Patent No. 1,644,363.

which consist in supplying to such persons while under compression a respiratory atmosphere composed principally of oxygen and nitrogen, the percentage of oxygen being less than that in air and such that when breathed under supernormal pressures irritation to the respiratory tract of oxygen poisoning will not occur, and supplying, while under decompression, a respiratory atmospherecomposed principally of oxygen and helium, the percentage of oxygen being less than that -in air and such that when breathed under supernormal pressures, irritation to the respiratory tract or oxygen poisoning will not occur.

16. In the treatment of persons undergoing extreme changes in pressure, the steps which consist in supplying to such persons while under compression a respiratory atmosphere composed principally of oxygen and nitrogen, the percentage of oxygen being less than that in air and such that when breathed under supernormal pressures irritation to the respiratory tract or oxygen poisoning will not occur, and supplying, while under decompression, a respiratory atmosphere composed principally of oxygen and a gaseous diluent having a solubility in body tissues and liquids less than that of nitrogen.

17. In the treatment of persons undergoing extreme changes in pressure, the steps which consist in supplying to such persons while under compression a. respiratory atmosphere composed principally of oxygen and nitrogen, the percentage of oxygen being less than that in air and such that when breathed under supernormal pressures irritation to the respiratory tract or oxygen poisoning will not occur, and supplying, while under decompression, a respiratory atmosphere composed principally of oxygen and a gaseous diluent having a greater rate of ditlusibility than nitrogen.

In testimony whereof we have hereunto set our hands.

WILLIAM P. YANT. ROYD R. SAYERS. JOEL H. HILDEBRAND.

of Correction.

Granted October 4, 1927, to

WILLIAM P. YANT ET AL. It is hereby certified that error appears in the printed specification of the abovenumbered patent requiring correction driver read dimer; and that the said rection therein that the same may conform to the record of the case in as follows: Page 2, line 127 for the word Letters Patent should be read with this corthe Patent M. J. MOORE,

Acting Commissioner of Patents.

Certificate of Correction.

Patent No. 1,644,363. Granted October 4, 1927, to

WILLIAM P. YANT ET AL.

It is hereby certified that error appears in the printed specification of the abovenumbered patent requiring correction as follows: Page 2, line 127, for the word driver read diver; and that the said Letters Patent should be read with this cur rection therein that the same may conform to the record of the case in the Patent Ufiice.

Signed and sealed th s 1st day of November, A. D. 1927.

[smirk] M. J. MOORE,

Acting Commissioner of Patents. 

